Such low abundances are in fact surprising and intriguing, as they cannot be easily explained by classical models of IGrM formation and enrichment. Although in some cases drops were found to be the result of spectroscopic biases [1]}, no evidence points toward the latter as being the sole explanation. Similarly, resonant scattering seems to be excluded from the culprit list in at least a few specific cases [2]}, and possible helium sedimentation – leading to an incorrect estimate of the continuum – should provide limited effects only, if not largely inhibited by thermal diffusion [3]}, [4]}. Interestingly, however, probing the chemical composition in the central low-Fe regions of these systems may provide an interesting hint toward the physical nature of these drops. This is further discussed in Sect. REF .
